Atlas said it currently had a relevant interest of 55.73 per cent in Giralia.

The deal is seen as an example of mergers and acquisitions being preferred over organic growth among resource players as development costs rise, driven by a tight labour market and rising capital costs.

Giralia directors have unanimously recommended all Giralia shareholders accept the offer, under which Atlas is offering one of its shares for every 1.5 Giralia shares, or alternative consideration of 1.33 Atlas shares plus 50 cents in cash.

Atlas said on Monday it would accelerate payment terms so Giralia shareholders who accepted the offer would be sent their consideration within three business days of their acceptance being processed. However, shareholders who had their shares acquired compulsorily, should Atlas get to 90 per cent, would not participate in the accelerated payment terms, it said.

Atlas is being advised by Hartleys head of corporate finance Grey Egerton-Warburton. Blake Dawson is providing the legal advice. Giralia is being advised by Credit Suisse; its legal adviser is Allion Legal.

Completion of the deal will see Atlas emerge with a market capitalisation of about $2.5 billion, up from a pre-bid market capitalisation of $1.6 billion. The offer is scheduled to close on February 28.